Carbon dioxide capture by means of reactive absorption-stripping using MEA is a very extensively studied process and its modeling represents an open issue in the specialized literature. In this thesis a rigorous rate-based model is developed in Aspen Plus environment. A new approach to the modeling based on the analysis of the system fluid dynamics is adopted. In this way, it is possibile to find the correct numerical solution of the system of equations derived from the material and energy balances. As part of the model development, the kinetic parameters of the reaction between CO2 and MEA are calibrated to minimize the standard error between the model results and the experimental data. The model is validated for both the absorber and the stripper considering several pilot-plant facilities with different sizes and operating conditions. Moreover, in the case of the stripper it is found that a correct model of the process leads to a significant improvement in the estimation of the reboiler duty. Subsequent to the model validation, the analysis of the design of an industrial scale plant is taken into account for different values of the lean solvent loading. In particular, a two-step procedure that consists in the evaluation of the minimum solvent flow rate with an infinite packing height and the subsequent evaluation of the effective solvent flow rate and packing height is used for the absorption column. Moreover, the operating conditions to avoid isothermal zones in the absorber are determined. When the stripper is considered, it is highlighted that the reboiler duty is needed to reverse the absorption reactions only. For this reason, an alternative plant configuration that reduces the energy consumption is adopted and a new criterion for the determination of the packing height is proposed for the stripping column. In the end, in order to obtain the minimum reboiler duty, it is found that the rich solvent, i.e., the stripper feed, must be sent at the highest possible temperature, which is limited by the minimum temperature approach in the cross heat-exchanger.

Modeling and Analysis of the CO2 Post-Combustion Process with MEA

MADEDDU, CLAUDIO
2018-03-19

Abstract

Carbon dioxide capture by means of reactive absorption-stripping using MEA is a very extensively studied process and its modeling represents an open issue in the specialized literature. In this thesis a rigorous rate-based model is developed in Aspen Plus environment. A new approach to the modeling based on the analysis of the system fluid dynamics is adopted. In this way, it is possibile to find the correct numerical solution of the system of equations derived from the material and energy balances. As part of the model development, the kinetic parameters of the reaction between CO2 and MEA are calibrated to minimize the standard error between the model results and the experimental data. The model is validated for both the absorber and the stripper considering several pilot-plant facilities with different sizes and operating conditions. Moreover, in the case of the stripper it is found that a correct model of the process leads to a significant improvement in the estimation of the reboiler duty. Subsequent to the model validation, the analysis of the design of an industrial scale plant is taken into account for different values of the lean solvent loading. In particular, a two-step procedure that consists in the evaluation of the minimum solvent flow rate with an infinite packing height and the subsequent evaluation of the effective solvent flow rate and packing height is used for the absorption column. Moreover, the operating conditions to avoid isothermal zones in the absorber are determined. When the stripper is considered, it is highlighted that the reboiler duty is needed to reverse the absorption reactions only. For this reason, an alternative plant configuration that reduces the energy consumption is adopted and a new criterion for the determination of the packing height is proposed for the stripping column. In the end, in order to obtain the minimum reboiler duty, it is found that the rich solvent, i.e., the stripper feed, must be sent at the highest possible temperature, which is limited by the minimum temperature approach in the cross heat-exchanger.
19-mar-2018
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/257330
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